Control circuit for broaching machines



Dec. 6, 1938. M; ROMAINE ET A; 2?.,`.l.'.9,l73

CONTROL CIRCUIT FORA BROACHING MACHINES Original Filed March l, 1953 3Sheets-Sheet l Dec. 6, 1938. M RQMAlNE ET AL 2,139,173

CONTROL CIRCUIT FOR BROACHING MACHINES original Filed March 1, '1953 3sheets-sheet 2 7 ljj 5 im JM, "f5 ya. i061 /Zf ATTORNEY.

De. 6, 1938. M, ROMAINE ET A1. 2,139,173

CONTROL CIRCUIT FOR BROACHING MACHINES Original Filed March l, 1953 3Sheets-Sheet 3 /I v ATTORNEY.

Patented Dec. 6, 1938 UNITED STATES PATENT OFFICE CONTROL CIRCUIT .FORBROACHING MACHINES Millard Romaine, Cincinnati, and Erwin Gr'.

Roehm, Norwood, Ohio, assignors to The Cincinnati Milling MachineCompany, Cincinnati, Ohio, a corporation of Ohio 14 Claims.

This invention relates to improvements in broaching machines and is adivision of our application therefor illed March 1, 1933, Serial Number659,226 and issued as Patent No. 2,063,756 on December 8, 1936.

One of the principal objects of the present invention is the provisionin connection with a breaching machine of the reciprocating type of an,improved hydraulic actuating mechanism for controlling the tooling andnon-tooling move- 4ments of the broach.

A further object of the present invention is the provision inconjunction with a machine tool of the character described of animproved 4hydraulic actuating circuit for effecting satisfactory toolingand facilitating rapid retraction of the broach or tool member.

Other objects and advantages of the present invention should be readilyapparent by reference to the following specification considered inconjunction with the accompanying drawings, forming a part thereof, andit is to be understood that any modications may be made in the exactstructural details there shown and described, within the scope of theappended claims, Without departing from or exceeding the spirit 'of theinvention.

In the drawings:

Figure 1 is a diagrammatic View of the complete hydraulic circuit andcontrols therefor.

Figure 2 is a sectional View illustrating the distributor and reversingvalve for controlling the movement of the hydraulic motor device.

Figure 3 is a sectional View taken on the line 3 3 of Figure 2.

Figure 4 is a sectional view through the balancing valve.

f Figure 5 is a sectional view taken on the line 5 5 of,` Figure 4.

Figure 6 is a fragmentary sectional view illustrating the valvecontrolling mechanism.

Figure 7 is a sectional view as on the line 'l-'I of Figure 6.

Figure 8 is a further sectional view as on the line 8-8 of Figure 6.

Figure 9 is a diagrammatic View similar to Figure '1 of the hydrauliccircuit and control therefor showing the system conditioned for rapidtraverse of the motor to the left, and

Figure 10 is a similar vieW showing the system conditioned forfeedingmovement of the motor in a right hand direction.

In view of the fact that the general structural details of the broachingmachine shown for purposes of illustration as actuable by our presentimproved hydraulic, circuit and described and claimed in detail in ourco-pending application above referred to, said general elements havebeen omitted herefrom with the exception that to facilitate generalunderstanding of the invention there has been illustrateddiagrammatically the cylinder A for the piston B having a piston rod Cengageable with the reciprocable broach carrier or the like D saidcylinder or hydraulic motor device potentially controllable by ourimproved mechanism as hereinafter described.

The hydraulic` system for effecting and controlling the movement of thepiston B'and consequently of the table D connected thereto, isdiagrammatically illustrated in Figure 1 and as there shown comprises asump or tank I for containing the uid, preferably oil, utilized in thesystem. In View of the large quantities of oil necessary to effect theoperation of the parts, there is shown a pair of pumps 2 and 3respectively having a suction line 4 and 5 for drawing the iiuiyd fromthe tank and discharging said fluid under pressure into conduits orlines Econnected with each pump.

A pressure control or relief valve 1 is provided for determining thepressure in the line 6 with which line is also connected a suitablegauge 8. The line 6 and its branch line 9 terminate in a valve,indicated generally bythe numeral I0 and constituting a directionalcontrol or reversing valve. The valve II) connects the line 6 or itsbranch line 9 with either of three conduits, Il, l2 and I3, the latterextending directly to the tank or sump I for short circuiting the systemand the other two terminating respectively at the right and left handends of the cylinder A.

The valve IIJ is shown in Figure 1 as in position to short circuit thesystem and return the fluid in the lines 6 and 9 to the sump or tank I.As also shown in this ligure, between the there is provided a secondvalve for permitting, when in the proper position, the rapid escape ofthe fluid from one side of the piston and indicated generally by thenumeral I4. This valve Ill is connected by a line or conduit I5 with theline or conduit I2 extending from the left hand end of the tablecylinder. The other side of the Valve i4 is connected by the line orconduit I6 with the conduit I3 terminating in the sump or tank I. Thevalves Ill and I4 are shown structurally in Figure 2 as enclosed withina single casing I1 having a pair of bores formed therein and disposedone above the other. Within the longer bore is the reversing valve whichcomprisesl a 40 reversing valve I0 and the piston and cylinder t v valvebushing I8 having formed therethrough sets of radial ports I9, 20, 2|,22, 23, 24, 25 and 26, each set being connected by a circumferentialgroove 21 formed on the exterior of the bushing. Extending through thebushing bore is a spool type valve 28 having cannelures 29, 3|] and 3|for connecting certain of the sets of radial ports in differentcombinations. The chamber containing the bushing |8 is closed atopposite ends by heads 32 and 33 which are substantially identical inconstruction and in each of which is mounted a guide 34 for a headedsleeve 35 and piston plungers 36 and 36a. rlhe guides 32 and 33 arefurther provided with chambered plugs 31 through which the head of thesleeve 35 shifts and connected with the outer ends of the plugs areconduits 38 and 38a of a control hydraulic system to be later describedand which effects the shifting of thevalve 28.

The releasable blocking valve I4, for relieving the back pressurefacilitating rapid exhaust of the hydraulic medium, is mounted in theshorter of the bores in the casing I1 and comprises a bushing 39 similarto the bushing |8 which has formed therethrough sets of radial ports 40,4|, 42, and 43. In the bore through the bushing is a spool type valve 44having a cannelure 45 adapted in one position to connect the sets ofports 4| and 42 and in the other position to interrupt the connectionthereof. The ends of the chamber containing the bushing 39 are closed inthe same manner as the ends of the chamber containing the bushing I8 andsaid closures each have mounted therein the piston plungers 46 and 41 ofdifferent-areas, whereby with equal pressures on the ends thereof, thevalve will be shifted by the larger piston plunger 41 for a, purposethat will be later made clear. 'I'he said chamber closures also includethe plugs 48 and 49 with which are respectively connected one terminusof conduits 50 and 5I which are a part of the control hydraulic circuit.

The hydraulic control circuit above referred to comprises a pump 52having a suction line 53 for drawing the hydraulic uid or medium fromthe tank I and discharging sam'e into the line or conduit 54. The line54 terminates at a pilot valve indicated in its entirety'in Figure 1 bythe numeral 55. The valve 55 is adapted in one position to connect thehydraulic medium with a pair of lines or conduits 56 and 51 whichrespectively terminate in lines or conduits 58 and 59. The conduit 58 inturn connects with conduits 38a and 5| respectively actuating the pistonplungers at the left hand ends of the valves, as seen in Figure 2, Whilethe conduit 59 connects the conduits 38 and 50 extending from the righthand ends of said valves. The valve 55 is also adapted, in differentpositions thereof, to connect the line 54 independently with either line56 or 51 and to connect the other with branch conduits or lines`60 and6I which terminate in a common discharge line 62 that has its terminusin the sump or tank I whereby the reversing or directional control valveand the blocking-power actuated relief valve are shifted to differentoperative positions.

The pilot valve 55 and mechanism for controlling and operating it isshown structurally in Figures 6, 7 and 8, particularly in Figure 7. Asthere shown, the valve comprises a casing 63 mounted Within a recess 64formed in a bracket 65. The valve casing 63 has formed thereinl a borein which is pressed thevalve bushing 66 having formed therethrough aplurality of sets of radial ports 61, 68, 69, 10 and 1| with which theends of conduits 68, 51, 54, 56 and 6I respectively connect. Extendingthrough the bushing 66 isa spool type valve 12 having formed thereoncannelures 13, 14 and 15 Which in the several positions of the valveconnect the conduits or complete the different circuits aboveenumerated. The valve 12 has formed integral therewith a stem in whichis formed a notch 16 receiving the ball end 11 of a load and fire dog18. The dog 18 is provided with two shallow notches 19 and 88intermediate which is a notch 8|. The several notches are connected bycontoured or cam shaped wells which co-operate with the nose' 82 of alatch 83 pivoted at 84 Within the recess 84 of the bracket 65. A spring85 has its one end anchored to the bracket 65 and its other endconnected with the latch 83 for yieldingly urging the latch about itspivot to cause engagement between the nose 82 thereof and the load andre dog 18.

The operation of the load and re dog is such that with the valve in theposition as shown in Figure '7, the latch 83 engages the shallow notch19 for holding the valve in its extreme left hand position and a slightmovement of the valve to the right will disengage the notch 19 andlatch, causing said latch to ride over the peak or apex of the joinedwalls of the notches 19 and 8| whereupon the valve Will be actuated toits neutral position until the latch is in the deep notch 8| thereof.When the valve is in its extreme right hand position, the latch isengaged with the shallow notch whereupon a slight movement of the dog o1valve in the opposite direction results in the reverse movement of theparts until the latch again comes to rest in the large or deep notch 8|.

The dog 18 is secured to a shaft 86 which spans the recess 64 andprojects beyond the limits of the bracket 65 and is journaled at one endin said bracket and on the other end in a plate 81 secured to the faceof the bracket 65. To the rear end of the shaft 86, which extends beyondthe journal thereof in the bracket 65, is secured an elongated arm 88having journaled in each end thereof a roller 89 and 90. The rollers 89and 90 are adapted to be respectively engaged by cam faces 9| and 92formed on reversing dogs 93 and 94 adjustable through slots 95 and 96formed in or secured to the side of the table D.

The operation of these parts is as follows: With the dog 18 in theposition shown in Figure 7 and the arm 88 in the position shown inFigure 8, the table D is moving to the right as seen in these figures.'I'he table carries with it the dog 93 the cam face 9| of which willeventually engage the roller 89 and tend to depress same therebyoscillating the arm 88, shaft 86 and dog 18 in a counterclockwlsedirection, unseating the latch 83 from the shallow notch 19 whereuponthe camming action or the firing of the latch 83 and d-og 18 by thespring 85 is had, as above described yfor returning the pilot valve toits normal or neutral position. The dog 81 and consequently the valve 12is initially shifted by manual means,

for which purpose the shaft 86 journaled in thev anism, the lever 91 hasthree positions, indicated in Figure 1 as rapid return, stop and feed.

CTI

` table.

The parts are shown with the lever 91 in its neutral or stop position atwhich time, as above described, the pressure from the pump 52 throughthe line 54 is connectedv by the cannelure 14 of the pilot valve 12 withthe conduits or lines 56 and 51. The same pressure will therefore be inthe lines 58 and 59 and consequently in'the conduits 5|, 50, 38a and 38.These conduitsdirect the pressure against piston plungers 41, 46, 36a,and 36. Since the piston plungers 36 and 36a are of the same'crosssection it will result in the centralization of the reversing valve u28,as shown in Figure 1, while since the piston plunger 41 is of a greatercross section than the piston 46, it will result in the valve 44 beingshifted to its extreme right hand position. At this time then thepressure in line 6 from the pumps 2 and 3 will be short circuitedthrough the branch line 9, cannelure 3| of the valve 28 with the returnconduit I3 which terminates in the sump or tank I, resulting thereforein no movement of the At the time of shifting of the piston plungers 36,36a, and 41 the hydraulic medium ahead of these plungers wasrespectively exhausted through ports I9, 26 and 43 Which respectivelyconnect with branch exhaust lines 98, 99 and |00 each of, which isconnected with a conduit or port and in turn emptying into a conduit orport |02 connected with a conduit |03 terminating in the sump or tank I.l

If the lever 91 is now shifted to the right or to the feed position, asshown in Figure 1, the pilot valve would be shifted to the left andthereby connect through the cannelure 14 the lines 54 and 56 and wouldconnect through the cannelure 13 the lines-51 and 60. At this time theconduit 58 and conduits 38a and 5| would be under pressure While theconduit 59 and conduits 38 and 50 would be connected to the exhaust.Since the rapid traverse valve 44 would already be to its right handlimitiof movement no further movement would be imparted thereto, but b yrelieving the pressure on the piston plunger 36 the reversing valve 28would be shifted to its extreme right hand position. This then woulduncover the port 23 and cover the port 25 so that the pressure in theline 6 would be coupled or connected through the cannelure 30 with theconduit I2 and act on the left hand face of the piston, thereby movingthe table to the right. At this time the exhaust ahead of the pistonwould be connected through the conduit II to the port 2| and through thecannelure 20 with the port 20 and a conduit |04 connected therewith. Theconduit |04 passes through a back pressure balancing valve indicated inits entirety by the numeral |05, which will be explainedin detail later.The table will continue to move in a direction toward the right at vafeeding rate of speed until one of the table dogs 92 or 93 engages withits roller on the arm 88 and thereby shifts the Valve to its neutral orstop position, whereupon the table will be brought to a standstill.

The lever 91 is now shifted to the left or to the rapid traverseposition for thereby connecting the control pressure line 54 with theline 51 and connecting the line 6| with the line 56. This thenreverses'the pressures in conduits 58 and 59 and consequently in thecontrol conduits to the piston plungers. In other words piston plungers46 and 36 are now under pressure for shifting the rapid traverse Valve44 to its left hand position and shifting the reversing valve 28 to itsleft hand position. At this time the charge pipe |30 with the sump ortank I.

Jfull capacity of the pumps 2 and 3 is being discharged into the smallend of the cylinder that is, the end through which the large piston rodis disposed. Since the capacity on both sides of the piston is therebygreatly changed, the piston and parts carried thereby will tend to moveat a rapid rate. And to insure that the oil or other hydraulic mediumcan escape fast enough from the large end of the cylinder, use is madenot only of the conduit I2 through the conduit I3, but also through thebranch conduit I 5 which is at this time connected with the conduit I6and conduit I3. From this it will be seen that the piston and partsoperated thereby are travelling at a rapid rate toward their initialposition. IThis movement continues until the other dog 03 or 94 on thetable engages the other of the rollers on the arm 88 and again returnsthe valve to its neutral or stop position.

The back pressure valve |05 is employed for' insuring a continuous evenmovement of the table and consequently the cutters and to eliminate anypossible surging or running ahead thereof. This valve is shownstructurally in Figures 4 and 5 and comprises a casing |06 having formedtherein a chamber containing the valve bushing this end of the bushingbore is a'plug II8 having threaded therein the screw ||9 forming one labutment for a spring |20 that abuts on? its other end with the pistonplunger I I1. Mounted 1n the bore of the bushing |01 on the other sideOf the valve |I4 is a shiftable abutment |2| contacted on one side `by aspring |22, whose characteristic and effective length may be varied bymeans of a screw |23 with the threads of which the spring I22 meshes.The screw |23 is threaded through a plug which closes this end of thebushing bore.

Referring now to the diagrammatic illustration in Figure 1, it will benoted that the normal discharge line from the reversing valve I0 hasextending from it three conduits |25, |26 and |21. Conduit |25 isconnected with'the bushing port I I3 and therefore places the pressureon the outer end of the piston plunger II1 equal to the pressure in theline I0. The conduit I26-connects with the port III and has a resistancetherein which is relatively low and consists of a coil or pipe I28having a comparatively small bore therethrough. The conduit, I21connects with the port IIlII and also has a hydraulic resistance thereinwhich is comparatively high as respects the hydraulic resistance I28 andalso comprises a coil I 29 having a bore thereinsmaller than that in thecoil |28'. The port IIII is connected by a dis- The ports |08 and II2are connected by branch conduits |3| and |32 with the discharge conduit|03 and constitute drains for draining the hydraulic medium that mayleak past the piston plunger II1 and spring abutment |2I.

The operation of this 'valve is as follows: When the table-is moving ina feeding direction the discharge of uid from the piston andcylinder-is, as above described, into the conduit I 04 from which itpasses through conduits |25, |26

and |21. Inasmuch as the chamber at the left hand end of valve |05,containing spring |20 into which the end of piston ||1 projects, and thechamber between the right hand end of valve |44 and the shiftableabutment I2I are closed chambers, under any condition of constantpressure in the general line |04, the pressure effects in these chamberswill be equal. Under these conditions, the right hand end of valve I|4having a greater area than the area of the piston plunger I I1, thepressure will tend tomove valve I I4 to the left, as viewed in Figures 1and 4. This would normally shut off the discharge port I I to line |30,preventing escape of the back pressure fluid through line |26,resistance |28. Therefore, to supplement the pressure action againstpiston I I1, use is made of the adjustable compression spring |20, alsoreacting on plunger II1, with the result that the combined effect ofpressure and spring action on plunger ||1 is sufficient in amount tocounterbalance the pressure effect through line |21 on the right handend of valve II4, causing a normal centralized positioning of the valve,as particularly brought out in Figure l, such that the exhaust fluidwill have an unrestrained return to reservoir through lines |26-|30.However, in the event there is a sudden surge in piston movement,tending to displace a larger amount of fluid than the normal flow forwhich the parts are adjusted, resistance |28 will effect an increase ofpressure in line |04 which will immediately react through line |25increasing the pressure effect against piston 1, moving valve |I4 to theright and thus increasing theA resistance to discharge through port III,maintaining the volumetric ilow a constant. The pressure increase thuscreated will also be effective in line 21, tending to force anadditional amount of the hydraulic fluid through line |21, resistance|29 into the space between the shiftable abutment |2| and the right handend of valve |I4. The fact that abutment |2| is positioned by theadjustable characteristic spring |22 permits this to act as anaccumulator when the initial pressure reaction against I I1 moves valve|I4 to the right and permits instantaneous throttling movement, in spiteof the fact that an increased pressure is being established through theresistance |29.

Conversely, when the pressure drops in line |04, the accumulatorabutment |2I reacting on the substantially trapped quantity of oil willhave an immediate effect to move valve I|4 to the left prior to thereverse drainage of a portion of the trapped fluid through. coil |29.

It will thus be seen that an improved pressure controlled ratedetermining valve structure has been provided which will insuredischarge of the exhaust medium at a constant rate irrespective ofexisting back pressure conditions or attempted volumetric dischargefluctuations.

.From the foregoing description considered in conjunction with theaccompanying drawings, the structure, operation and advantages of ourimproved hydraulic control system as particularly applicable tobroaching machines or other machine tools, should be clearly understoodand it will be noted that we have provided an improved systemparticularly adapted for preventing surging of a movable tool during thecutting operation and for facilitating the rapid return thereof for anew cutting stroke.

What is claimed is:

1. An hydraulic circuit for control of the piston and cylinder mechanismof a machine tool including an hydraulic medium for operating the pistonand cylinder, a reversing valve in said circuit for selectively directlythe pressure medium to opposite ends of the cylinder, an hydrauliccontrol circuit including a pilot valve for controlling the position ofthe reversing valve, a manually operable direction indication levercoupled with the pilot valve for operating same and simultaneouslyindicating the direction of movement of the table, aback pressurecontrol valve in the circuit for controlling the back pressure from thepiston and cylinder to insure uniform rate of movement of the tableduring feeding, a valve in the circuit for controlling the discharge ofthe medium from the other end of the cylinder and connections betweenthe pilot and said valve for actuating the latter as the pilot isshifted to effect reversal of table operation whereby rapid movement ofthe table when moving in the opposite direction is facilitated.

2. An hydraulic circuit for control of the piston and cylinder mechanismof, a machine tool including an hydraulic medium for operating thepiston and cylinder, a reversing valve in said circuit for selectivelydirecting the pressure medium to opposite ends of the cylinder, anhydraulic control circuit including a pilot valve for controlling theposition of the reversing valve, a manually operable directionindication lever coupled with the pilot valve for operating same andsimultaneously indicating the direction of movement of the table, a backpressure control valve in the circuit for controlling the back pressurefrom the piston and cylinder to insure uniform rate of movement of thetable in one direction, a valve in the circuit for controlling thedischarge of the medium from the other end of the cylinder to permit arapid movement of the table when moving in the opposite direction, andmeans connecting the said valve with the pilot valve whereby theposition of the valve is determined by the adjustment of the pilotvalve.

3. An hydraulic motor control system of the character describedincluding a source of hydraulic pressure medium including a transmittingconduit, a pair of motor conduits, a reversing valve intermediate theseveral conduits for selectively coupling the pressure transmittingconduit with one or the other of the motor conduits, said reversingvalve having an intermediate stop position, means for selectivelypositioning the reversing valve in either of said three posi-l tions, ablocking valve permanently associated with one of the motor conduits, areservoir connection associated with the blocking valve whereby themotor conduit is connected to reservoir when said valve is moved tounblocking position, and connections between the reversing valve andblocking valve effective to maintain the blocking valve in closedposition as respects two positionings of the reversing valve and toshift the valve to unblocking position affording an outlet to reservoirwhen the reversing valve is moved to its third effecting position.

4. An hydraulic circuit for actuation of a piston and cylinder mechanismincluding a reversing valve for alternately connecting the circuit withopposite ends of the piston and cylinder mechanism, a pressure by-passvalve in the circuit for relieving the back pressure in one end of thecylinder to permit a rapid movement in one direction, hydraulicallyactuated pistons for reversely shifting said reversing and pressurebypass valves, the pistons on the pressure by-pass valve being ofunequal area whereby the said valve is by application of pressure tobothpistons thereof actuated in one direction, and a separate hydrauliccontrol circuit including a control valve having portions for directingthe pressure simultaneously to one or the other of the pistons of thereversing and pressure by-pass valves whereby the said valves aresimultaneously shifted in accordance therewith, said control valvehaving portions for simultaneously connecting the pressure to, both ofthe pistons of the valves for moving said valves into a positionhydraulically to lock the piston and cylinder in a given position.

5. A control mechanism for a reversible hydraulic motor, including asource of hydraulic actuating medium, a pair of conduits oppositely`coupled with the motor for input or withdrawal of actuating mediumtherefrom, a three-position reversing valve intervening said source andthe conduits for selective couplingof either of said conduits with themotor for actuation thereof, a two-position reservoir connection controlvalve associated with one of said motor conduits, balanced pistonmembers oppositely associated with the reversing valve for actuationthereof, whereby pressure against either of the pistons will effectmaximum movement of the valve in one direction or the other, while equalpressuresl will effect centralization of the valve, and unbalancedpiston members oppositely associated with the reservoir valve wherebyequal pressures will cause a positive closing movement thereof, and acornmon pilot circuit for the pistons of both valves whereby pressuremay be selectively correspondingly directed against the pistons ateither or both termini of both of said valves, substantially as and forthe purpose described.

6. In an hydraulic mechanism of the character described, the combinationwith a reversely hydraulic motor including a pair of conduits oppositelyconnected to the motor and alternatively employable for introduction inor exhaust of actuating hydraulic medium therefrom, of a normally closedreservoir connection for one of said conduits, a reservoir connectioncontrol valve therefor, a rate determining valve selectively coupleablewith the other of said conduits, a control valve member forsimultaneously coupling the hydraulic actuating medium with one of saidconduits and coupling the other of said conduits with the ratedetermining valve, and means for simultaneously shifting the controlvalvejmember and the reservoir connection control valve.

7. Ilhe combination with a reversible hydraulic motor, of means forcontrolling the rate and direction of actuation thereof "including asource of hydraulic medium under pressure, conduits oppositely coupledto the motor for conduction of medium to one side or the other thereoffor effecting its reverse actuation, a first valve means shiftable intoa position to couple the-medium with one or the other of said conduitsand into a third position to disconnect the medium from both of saidconduits, a back pressure control valve, said rst mentioned valve havinga portion eective in one position to couple one of the motor conduits tosaid back pressure control valve when the other of the motor conduits iscoupled yto pressure whereby said back pressure control sitionings ofsaid rst and third valves, said means including a rst set of pistondevices operatively related to the first mentioned valve effective toshift the same to an extreme position in one directionor the other whensubject to hydraulic pressure, a second set of' limited movement pistonsassociated with said rst valve and effective when simultaneouslysubjected to pressure to shift said first valve to an intermediateposition, opposed actuating .pistons of unequal areas associated withthe' third valve whereby when the piston of greater area is subject topressure either alone or in conjunction with the .exertion 4ofcorresponding pressure against the other piston, said third valve willbe shifted thereby in a given direction and will be hydraulicallyshiftable in the opposite direction only in the absence of pressureagainst the piston of greater area, a rst hydraulic control circuitcoupled in parallel with one pair of pistons of the first valve and oneof the pistons of the third valve, a second hydraulic control circuitcoupled in parallel with the other pistons of the first valve and thirdvalve, and means for selectively directing pressure individually toeither or both of said control circuits for effecting variablepositonings of said first and third valves, substantially as and for thepurpose described.

8. The combination with a reversible hydraulic motor, of means forcontrolling the rate and direction of actuation thereof including asource of hydraulic medium under pressure, conduits oppositely coupledto the motor for conduction of medium to one side or the other thereoffor effecting its reverse actuation, a first valve means shiftable intoa position to couple the medium with one or the other of said conduitsand into a third position to disconnect the medium from both of saidconduits, a back pressure control valve, said first mentioned valvehaving a portion eifective in one position to couple one of the motorconduits to said back pressure control valve when the other of the motorconduits is coupled to pressure whereby said back pressure control valvewill determine the back pressure resistance to actuation of the motor,an auxiliary reservoir connection for the opposite motor conduit, valvemeans normally blocking the flow through said auxiliary reservoirconnection, and hydraulically actuable means for determining theeffective positionings of said rst and third valves, said meansincluding a rst set of piston devices operatively related to the firstmentioned valve effective to shift the same to an extreme position inone direction or the other when subject to hydraulic pressure, a secondset of limited movement pistons associated with said first valve andeffective when simultaneously subjected to pressure to shift said firstvalve to an intermediate position, opposed actuating pistons of unequalareas associated with the third valve whereby when the piston of greaterarea is subject to pressure either alone or in conjunction with theexertion of corresponding pressure against the other piston, said thirdvalve will be shifted thereby in a given direction and will behydraulically shiftable in the opposite direction only in the absence ofpressure against the piston of .greater area, a rst 'hydraulic controlcircuit coupled in parallel with one pair of pistons of the first valveand one of the pistons of the third valve, a second hydraulic controlcircuit 4coupled in parallel with the other pistons of the first valveand third valve, means for selectively dlrecting pressure individuallyto either or both 0f 75 said control circuits for effecting variablepositionings of said first and third valves, trip operable means fordetermining the effective action of the control circuit coupling means,and trip devices shiftable by the motor for actuation of said tripoperable means.

9. In a-mechanism of the character described, the combination with areversible hydraulic motor and a source of actuating pressure therefor,a pair of conduits coupled with opposite ends of the motor, anintervening control mechanism including a first Valve mechanism havinginlets from the source of pressure and outlets to both of said conduits,said valve mechanism including a shiftable part movable to a firstposition to couple one of said conduits to pressure, to a secondposition disconnecting pressure from vboth of said conduits, and a thirdposition coupling the pressure to the other of said conduits, said valvebeing further provided with an exhaust flow conduit, means on themovable member effective in one position thereof for coupling one ofsaid motor conduits to the exhaust conduit, an auxiliary exhaustconnection for the other motor conduit including a valve for preventionof flow through saidexhaust conduit, and an hydraulic couple betweensaid valve and the movable member of the'iirst mentioned valve wherebysaid valves are simultaneously actuable, said valves having portingsinversely effective as respects establishment of exhaust connectionstherethrough for the respective motor conduits.

10. In a hydraulic transmission of the character described, a backpressure line control valve including a pressure actuable throttlingdevice for varying the effective discharge passage through the valve, adirect pressure connection subject to varying conditions in the backpressure line coupled with the valve for reaction in a direction toincrease the restriction thereof, an

accumulator associated with the valve for yieldingly resisting saidclosing action, and means for effecting variable pressures in saidaccumulator.

1l. In a hydraulic transmission of the character described, a backpressure line control valve including a pressure actuable throttlingdevice for varying the effective discharge passage through the valve, adirect pressure connection subject to varying conditions in the backpressure line coupled with the valve for reaction in al direction toincrease the restriction thereof, an accumulator associated with thevalve for yieldingly resisting said closing action, means for effectingvariable pressures in said accumulator, said means including a hydrauliccouple between the back pressure line and the accumulator, and means inthe couple for effecting a .time delay in the pressure variations of theaccumulator as respects pressure variations in the direct pressureconnection.

12. In a hydraulic transmission of the character described, thecombination with the motor of a back pressure conduit extendingtherefrom, means for controlling both constant and surge effects ofdischarge in the back pressure line comprising a valve body having inletand discharge ports, a valve therein shiftable variably to restrict thedischarge from the back pressure line by way of said ports, a plunger,resilient means for urging the plungerinto engagement with the valve foreffecting a restrictive movement thereof, means impoundintg` a backpressure fluid adjacent the plunger whereby the latter has an'hydraulicpiston effect supplementing the yielding means in urging the valve intoa restricting position, said valve having a piston portion effective inopposition to the plunger and of greater area than said plunger, meansproviding a chamber enclosing the piston, and means coupling the backpressure to said chamber for reactance on the piston, said meansincluding a resistance creating pressure drop during flow of liquid intothe chamber, whereby a temporary differential in the effective pressureson the plunger and piston is created, substantially as and for thepurpose described.

13. In a hydraulic transmission of the character described, thecombination with the motor of a back pressure conduit extendingtherefrom, means for controlling both constant and surge effects ofdischarge in the back pressure line comprising a valve body having inletand discharge ports, a valve therein shiftable variably to restrict thedischarge from the back pressure line by way of said ports, a plunger,resilient means for urging the plunger into engagement with the valvefor effecting a restricting movement thereof, means impounding a backpressure fluid adjacent the plunger whereby the latter has an hydraulicpiston effect supplementing the yielding means in urging. the valve intoa restricting position, said valve having a piston portion effective inopposition to the plunger` and of greater area ythan said plunger, meansproviding a chamber enclosing the piston, means coupling the backpressure to said chamber for reactance on the piston, said meansincluding a resistance creating pressure drop during flow of liquid intothe chamber, whereby a temporary differential in the effective pressureson the plunger and piston is created, said chamber forming meansincluding a shiftable element for varying the effective size of thechamber, and yieldable means urging said member in a direction to reducethe effective area of the chamber substantially as and for the purposedescribed.

14. In a hydraulic transmission of the character described, thecombination with the motor of a back pressure conduit extendingtherefrom, means for controlling both constant and surge effects ofdischarge in the back pressure line comprising a valve body having inletand discharge ports, a valve therein shiftable variably to restrict thedischarge from the back pressure line by way of said ports, a plunger,resilient means for urging the plunger into engagement with the valvefor effecting a restricting movement thereof, means impounding a backpressure fluid adjacent the plunger whereby the latter has an hydraulicpiston effect supplementing the yielding means in urging the valve intoa4 restricting position, said valve having a piston portion effective inopposition to the plunger and of greater area than said plunger, meansproviding a chamber enclosing the piston, means coupling the backpressure to said chamber for reactance on the piston, said meansincluding a resistance creating pressure drop during flow of liquid'intothe chamber, whereby a temporary differential in the effective pressureson the plunger and piston is created, said chamber forming meansincluding a shiftable element or varying the effective size of thechamber, yiidable means urging said member in a direc ion to reduce theeffective area of the chamber, and means for individually adjusting theyielding pressure devices oppositely effective as respects said passagerestricting valve.

LUILARD ROMAINE.

ERWIN G. ROEHM.

